. >> president obama and the first lady are in route to south africa where nearly 90 world leaders are expected to attend tomorrow's memorial service for nelson mandela. also on air force one, former president george w. bush, his wife laura and former secretary of state hillary clinton. former presidents bill clinton and jimmy carter are traveling separately. the only living president not able to attend george h.w. bush, at 89 can no longer travel such a long distance. it will be held in soweto where nelson mandela made his final public appearance in 2010. ron, you have half of the world's leaders gathering, that stadium seats 95,000. it is an open air and presented significant challenges security wise. >> reporter: yes, there's perhaps not been an event like this ever, dare i say, the most comparable is the funeral of pope john paul ii in 2005 where there was 3 million people and 75 or 80 world leaders who attended. this is going to be an amazing day tomorrow. there's a lot of anticipation already. behind me you can hear people in the streets here still singing and dancing and sell br